Seemingly all Facebook-owned services, including Facebook, Instagram, WhatsApp, and virtual reality platform Oculus have been down for more than an hour. 

“We’re aware that some people are having trouble accessing our apps and products,” Facebook said in a tweet. “We’re working to get things back to normal as quickly as possible, and we apologize for any inconvenience.” 

Users on Hacker News, a Reddit-like message board frequented by many Silicon Valley workers, are speculating that this is a DNS problem. Major web services go out from time to time, but Facebook has billions of users across its platforms and a broad outage like this lasting more than an hour is quite rare. 

John Graham-Cumming, CTO for internet infrastructure company Cloudflare, tweeted a screenshot of what it looked like when Facebook suddenly went down, and the knock-on effects for his company. “Good reminder that the internet is a network of networks that works through standards and cooperation,” he tweeted.

In the past, outages that have affected huge swaths of the internet have often had to do with misconfigurations on Amazon Web Services, major denial-of-service attacks on internet infrastructure companies, or some other sort of problem with internet infrastructure company configurations. At the moment, Facebook's products seem to be the only sites experiencing major outages according to DownDetector, suggesting it may be a problem with Facebook itself.

Facebook did not respond to a request for comment.